Drafting apparatus



i July29, 1947. w. H. MURPHY .27,424,840

DRAFTING APPARATUS Filed April 1o, 1944l 2 sheets-sheet 1 July .29,1947# I w. H. MURPHY DRAFTING APPARATUS Filed April 1o, 1944 2Sheets-Sheet 2 Patented July 29, 1947 UNITED STATES PATENT OFFICEDRAFTING APPARATUS William H. Murphy, Chicago, Ill.

Application April 10, 1944, Serial No. 530,243

6 Claims.

My invention relates generally to drafting apparatus and moreparticularly to improved apparatus of this character having auniversally adjustable head mounted for transverse movement on a mobilestraightedge.

It is an object of my invention to provide an improved draftingapparatus which may be easily adjusted to facilitate drawing lines atany desired angle and at any position upon the drafting board or table.

A further object is to provide an improved drafting apparatus which isvery simple in construction and may be produced at a much lower costthan comparable apparatus made in the past,

Other objects will appear from the following description, referencebeing had to the accompanying drawings, in which Fig. 1 is a plan viewof a drawing board with the improved apparatus of my invention installedthereon;

Fig. 2 is an enlarged plan view of a slightly modified form of theinvention, in that the protractor head is provided with but a singlearm;

Fig. 3 is a rear plan view of a portion of the apparatus shown in Fig.2;

Figs. 4 and 5 are enlarged sectional views taken on the lines 4--4 and 55, respectively, of Fig. 2;

Fig. 6 is a fragementary sectional view taken on the line 6-6 of Fig. 4and showing the head clamping means in clamping position; and

Fig. 7 is a view Similar to Fig. 6, showing the parts of the clampingmechanism in released position.

Referring to Fig. 1, the apparatus of my invention is illustrated asbeing mounted upon a drafting board, or table, III, which may be of anysuitable construction, and which is equipped with a mobile straightedgeI2. This straightedge is preferably of the general construction shown inthe patent to H. L. De Lisle, No. 2,256,241, As shown in greater detailin said patent, the mobile straightedge I2 is constrained fortranslatory movement by means of cables I4 and I6, the ends of which arejoined by a spring slack take-up device I8, and the opposite ends ofwhich are respectively anchored to the board or table I at the loweredge thereof. The cable I6 passes around a pulley which includes asuitable cable clamp 22 normally engaged with the cable to preventmovement of the cable I6 around the pulley 20.

When it is desired to have the straightedge I2 positioned at an angle tothe horizontal edge of the board IU, the clamp 22 may be released and 2the straightedge I2 then adjusted tothe desired angle, whereupon theclamp 22 is reengaged. Thereafter, the straightedge I2 will betranslatable upwardly and downwardly on the board Ill, but will maintainthe set angularity with respect to the horizontal edge of the board.

As best shown in Figs. 4 and 5, the straightedge I2 comprises a strip 24of a suitable nonwarping plastic material, such as Formica XX, with araised shoulder portion 24a which is shown as formed of a separate stripof material cemented thereto and upon which a complementary strip 26 issecured by a plurality of drive screws 28, The edges of the strip 24 aregrooved for the reception of transparent plastic ruler edges 30, 3l,which may be secured in place by a suitable adhesive. The contactingfaces of the strips 24a and 26 are provided with opposed grooves forminga passageway 34 for the operating cables I4 and I 6.

The longitudinal edges of the strip 26 are undercut to provide way orguide surfaces for complementally beveled washers 36 secured to aprotractor body 38 by screws 40, and for engagement by a clamping bar 42having a beveled edge 44. A strip or shoulder 24a is reversely andcomplementarily beveled on its longitudinal edges with respect to theundercut edges of strip 26, and in the form illustrated is extendedlaterally slightly beyond the meeting edges of strip 26. The clampingbar 42 is mounted for lateral sliding movement with respect to theprotractor body 38 by means of a pair of rivets 46 which are laterallyslidable in slots 48. As best shown in Figs. 6 and 7, the bar 42 ispressed against the beveled edge of the strip 26 by a bowed wire spring'50, the ends of which fit in suitable sockets 52 formed in the bar 42,and the central portion of which reacts against a screw 54.

The bar 42 is adapted to be moved laterally to cause its beveled edge 44to be disengaged from the adjacent under-cut edge of the strip 26suicently to permit removal of the protractor head 38 from thestraightedge. The means for accom.- plishing such movement of the :bar42 comprises a manually operable lever 56 secured to a crankshaft 58mounted for pivotal movement in the head 38; The crank portion of theshaft 58 projects into a longitudinal slot 60 formed in the bar 42 sothat upon rotation of the lever -56 from its normal horizontal position(Fig. 2) to a substantially vertical position (Fig. '7), the bar 42 ismoved laterally against the resilient force of the spring 50 a su'icientdistance to free the edge 44 of the clamping bar 42 from the adjacentunder- 3 cut beveled edge of the strip 2B of the straightedge. When theclamping bar 42 is moved to this position, as shown in Fig. 7, theprotractor head may be removed from the straightedge.

The body 33 of the protractor head is drilled to receive a headed socketmember E2 which is internally threaded to receive a stud 64 which may bemolded as an insert in a knob 6B. The movable part 68 of the protractoris pivoted on the socket 62. and is frctionally clamped to the body 38vby an undercut Washer 1G. The protractor part 68 ts closely in acomplemental recess 12 formed in the upper surface of the body 38, andthe upper surface of the protractor part 68 has angular degreegraduations 14 marked thereon in a suitable manner, these. graduationscooperating with Vernier graduations 1.6 marked on the upper surface ofthe body 38 adjacent the graduations 14.

The protractor part 68 may be provided with a single arm 18 as shown inFigs. 2 and 3, or may have a. pair of mutually perpendicular arms 8l).

'In each instance, the arms 18 and 80 are provided with suitabledovetail slots for the reception of complementary parts on ruler arms82, so that the latter may be detached whenever desired.

From a consideration of the fact that the mobile straightedge 2 may beadjusted for translatory movement while at any desired inclination tothe horizontal, it. will be clear that the apparatus may be used withgreat convenience in the making of drawings having a non-horizontal baseline. In making such drawings, the mobile straightedge l2 is adjusted tolie parallel to the base line andl the apparatus may then be used to.draw lines. at predetermined angles with respect to. the base line, bysetting the protractor part 6a at such angle with respect to the O markof the Vernier graduations 16. The making of drawings of this type isthus facilitated as compared with making` them with a conventionaldrafting machine, in. that all angular dimensions may be read direct-1yfrom the graduations. 14, whereas in the conventional drafting machine.such angular dimensionswould have to bev computed from the scalereading` of the machine by adding or subtracting the anglev by which thebase line deviates from the horizontal.

'The spring 50., through the bar 42, secures the body 38- of theprotractor head iirmly to the straightedge so that it will not tiltrelative thereto, and applies sufficient clamping force to producefriction between the bar 42 and the strip 26. so that. the head will notbe liable to accidental displacement from the position on thestraightedgeY I 2v to which it is set. Whenever the protractor head isnot to be used it may readily be disengaged from the straightedge I2merely by swinging the wing lever 55 to a vertical position, whereuponthe bar 42 will be moved out of the` undercut bevel of the straightedgesufficiently to perm-.it the protractor head to be raised and removedfromv the straightedge l2. Similarly, the head. may be easily andquickly attached to the straightedge.

While 'I' have shown and described particular embodiments of myvinvention, it will be apparent that numerous variations andmodifications thereof` may be made without departing from the underlyingprinciples of the invention. I therefore desire, by the followingclaims, to include within the scope4 of my invention, all suchvariationsA and modications by which substantially the results ot myinvention may be obtained 4 through the use of substantially the same orequivalent means.

I claim: 1. In combination, a straight-edge having under-cutlongitudinal edges, a protractor member slidably mountedY on saidstraight-edge and having retaining members engaging beneath one of saidunder-cut edgesl and an engaging member slidably mounted upon saidprotractor head and provided with means movable into and out of positionengaging beneath the other of said under-cut edges.

2. In combination, a straight-edge having under-cut longitudinal edges,a protractor member slidably mounted on said straight-edge, and havingretaining members engaging beneath one of said under-cut edges, anengaging member slidably mounted upon said protractor head and providedwith means movable into and out of position engaging beneath the otherof said under-cut edges, and spring means coacting with said last namedmember to urge the same into engaging position.

3.. In combination, a straight-edge having under-cut longitudinal edges,a protractor member slidably mounted on said straight-edge, and havingretaining members engaging beneath one of said under-cut edges, anengaging member` slidably mounted upon said protractor head and providedivith means movable into and out of position engaging beneath the otherof said undercut edges, spring means coacting with said last namedmember to urge the same into engaging position, and means manuallyoperable to retract-l said last named member against the action of saidspring to permit disengagement of said. protractor from saidstraight-edge,

4. A straight-edge, a protractor slidably mounted thereon, said straightedge being provided with under-cut longitudinal edges, said pro.-tractor being provided with retaining members engageable beneath one ofsaid under-cut edges, said protractor member additionally beingAprovided with slots, securing members slidably 45 mounted in said slotsand headed at one end to prevent disengagement from said protractormember, an engaging member carried by said securing members at theiropposite ends and movable into and out of position engaging beneath 50the other of said under-cut edges, and means yieldingly urging saidsecuring member in engaging position.

5. A straight-edge, a protractor slidably mounted thereon, saidstraight-edge being pro- 55 vided with' under-cut longitudinal edges,said protractor being provided with retaining members engageable beneathone of said under-cut edges, said protractor member additionally beingprovided with slots, securing members slidably 60 mounted in said slotsand headed at-onev end to prevent disengagement from said protractormember, an engaging member carried by saidjsecuring members at theiropposite ends and movable into and out of position engaging beneath 65the other of said, under-cut edges, means yieldingly urging saidsecuring member in engagingl position, said last named. means comprisinga, spring member and a pin` coacting therewith and carried by saidprotractor member.

6. A straight edge, a protractor slidably mounted thereon, said straightedge being provided with undercut longitudinal edges, said protractorbeing provided with retaining members engageable beneath one ofsaidunder-cut edges.. 75 said protractor member additionally beingprovided with' slots, securing members slidably mounted in said slotsand headed at one end to prevent disengagement from said protractormember, an engaging member carried by said securing members at theiropposite ends and movable into and out of position engaging beneath theother of said under-cut edges, means yieldingly urging said securingmember in engaging position, and means to disengage said engaging membercomprising a manually operable eccentric member carried by saidprotractor member and engaging said engaging member.

WILLIAM H. MURPHY.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number Number UNITED STATES PATENTS v Name Date Graves Apr. 7, 1942Linsner Sept. 18, 1923 De Lisle Sept. 16, 1941 Fatkin Oct. 26, 1943Christian May 25, 1926 FOREIGN PATENTS Country Date French Oct. 23, 1925Great Britain A. D. 1943 Germany Dec. 28, 1926

